PROJECT SUMMARY The sxRNA Technology is conceptually based on the binding of one RNA molecule to a second RNA molecule in a manner that predictably ?switches? the structural confirmation of the first RNA. As a demonstration of the potential of sxRNA technology, we have used the presence/absence of a microRNA as a ?trigger? to turn ON the translational activity of an ectopically delivered Bait-mRNA sequence to create the binding-motif for an endogenous RNA-Binding Protein (RBP). Once the RBP is recruited to the now functional motif, translation of the mRNA is activated to produce any protein of interest. Thus sxRNA can be used for the transient expression of an ectopically delivered mRNA based on the presence of distinctively expressed microRNAs. The current sxRNA technology has been reduced to practice based around a modular design comprised of the switchable bait-RNA structure (Aim 1), the trigger-RNA (Aim 2) and the tethered open reading frame coding for a gene of interest (Aim 3). The long-term objective of this Focused Technology Research and Development grant is to fully develop the sxRNA technology so that it can be utilized to its broadest potential for Public Health. Accordingly, the Aims are designed to facilitate the comprehensive development, optimization and improvement of each of the modules of the existing sxRNA technology and expand the potential as a new RNA-based molecular resource with multiple applications including as a real-time, single-cell sensor of microRNA expression, as a tool for targeted cell/tissue selection, in stem-cell differentiation and manufacture, for biomanufacturing, as an anti-viral/bacterial technology and as a new RNA-based tool for cell and tissue bioimaging.